Healthtap has received $24 million in series B funding from a number of high-profile venture firms, as well as gaining some heavyweight advisers.

Khosla Ventures led the round, in which previous investors Mayfield Fund and Mohr Davidow Ventures joined in. Also, Khosla partner, and former chief operating officer of Square, Keith Rabois, is joining Healthtap’s board. Vinod Khosla is now acting as an adviser.

Healthtap has built up a network of doctors, 38,000 in total, who answer patient questions via online and mobile apps. The company is led by CEO Ron Gutman (pictured).

Part of the attraction for investors is the timeliness of Healthtap’s approach. The US healthcare system is set to come under pressure from an influx of additional patients following the passing of the Obama administration’s Accordable Care Act, which is intended to open the system to more people.

The company described its new financing as “one of the most substantial series B investments to date in the digital health industry”.

It will use the new backing to acquire more staff, expand its web and mobile offerings, and build on its rapid growth.